Abstract: A safety switch assembly for use in filling a gasoline products tanker and having a body portion and a gasoline level sensing portion. A channel (part-circular in plan) in the body portion fits over the rim of the filler opening of the tanker to enable the rim to actuate a first electrical switch contained in the body portion. The sensing portion projects into the filler opening and includes a reed relay and a float carrying a magnet to actuate the reed relay. The first electrical switch is a double pole microswitch having one pole normally open and the other pole normally closed. The normally open pole is connected to delivery apparatus to prevent delivery unless the rim actuates the microswitch. The normally closed pole is in parallel with the reed relay which has its contacts closed when the float is unactuated. When the gasoline level nears the top of the container the float rises to de-actuate the reed relay and disable the delivery system to prevent spillage.